[PATCH] Add timeout to _poll_loop function to avoid infinite looping

[Jiri Prochazka]

When Slave is using NetworkManager, polling is used to activate DBus connection.
This may result in infinite loop (eg. when device is not in LOWER_UP state, but is in UP
state).
This patch adds timeout control in _poll_loop method, timeout value is set to 10s.

Signed-off-by: Jiri Prochazka <jprochaz(a)redhat.com&gt;
---
 lnst/Slave/NmConfigDevice.py | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/lnst/Slave/NmConfigDevice.py b/lnst/Slave/NmConfigDevice.py
index 8e2f1dd..3da54f1 100644
--- a/lnst/Slave/NmConfigDevice.py
+++ b/lnst/Slave/NmConfigDevice.py
@@ -153,10 +153,14 @@ class NmConfigDeviceGeneric(object):
             self._loop.quit()
 
     def _poll_loop(self, func, expected_val, *args):
-        while True:
+        timer = 0
+        while timer < 10:
             if func(*args) == expected_val:
-                break
+                return
             time.sleep(1)
+            timer += 1
+        msg = "Timed out during NetworkManager polling."
+        raise Exception(msg)
 
     def _convert_hwaddr(self, dev_config):
         if "hwaddr" in dev_config:
-- 
2.4.3

[Ondrej Lichtner]

On Mon, Jun 29, 2015 at 04:06:40PM +0200, Jiri Prochazka wrote:
>  When Slave is using NetworkManager, polling is used to activate DBus
> connection.
>  This may result in infinite loop (eg. when device is not in LOWER_UP state, but is in UP
> state).
>  This patch adds timeout control in _poll_loop method, timeout value is set to 10s.
>  
>  Signed-off-by: Jiri Prochazka <jprochaz(a)redhat.com&gt;
>  ---
>   lnst/Slave/NmConfigDevice.py | 8 ++++++--
>   1 file changed, 6 insertions(+), 2 deletions(-)
>  
>  diff --git a/lnst/Slave/NmConfigDevice.py b/lnst/Slave/NmConfigDevice.py
>  index 8e2f1dd..3da54f1 100644
>  --- a/lnst/Slave/NmConfigDevice.py
>  +++ b/lnst/Slave/NmConfigDevice.py
>  @@ -153,10 +153,14 @@ class NmConfigDeviceGeneric(object):
>               self._loop.quit()
>   
>       def _poll_loop(self, func, expected_val, *args):
>  -        while True:
>  +        timer = 0
>  +        while timer < 10: 
                        ^^^^
This should be a parameter of the function not just a random constant...
And there should be a defult value constant at the start of the file
where other NM related constants are defined.

>               if func(*args) == expected_val:
>  -                break
>  +                return
>               time.sleep(1)
>  +            timer += 1
>  +        msg = "Timed out during NetworkManager polling."
>  +        raise Exception(msg)
>   
>       def _convert_hwaddr(self, dev_config):
>           if "hwaddr" in dev_config:
>  -- 
>  2.4.3
>  
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